Boldness and American football

The comforts of failure

DOES any aspect of American football excite less interest than punting? Occasional moments of comic glory notwithstanding, punting is, in essence, a hedged bet. It is an admission not just of failure, but of fear of failure: through the play the coach expresses his doubt in his team’s ability to move the ball the requisite number of yards, and the belief that it is preferable to just give the ball to the other team and play for position rather than making them take it.

Punting is also, according to the New York Times’s new 4th Down Bot, usually the wrong decision. The bot crunches data from plays over the past 13 years to determine the optimal call for any given fourth down. It uses a measure called “expected points”, which assigns a point value to any situation based on how likely a team is to score. On first-and-10 from its own goal line, for instance, a team has negative expected points: its opponent is likelier to score. The closer the team draws to its opponent’s goal line, the closer its expected points get to six (the value of a touchdown). Determining a fourth-down play’s expected-points value is more complicated than it seems: a coach must take into account not just how likely his team is to score, but how likely the opposing team is to score on the next play.

To use the article’s example: it’s fourth-and-10 on an opponent’s 38-yard line. A coach can either punt, go for a first down or kick a field goal. The average punt from the 38 would put the opponent on his own 14-yard line, giving the opponent 0.04 expected points. That outcome is thus worth -0.04 expected points to the coach’s team. A field goal is worth three actual points, but just 2.6 expected points (the three minus the 0.4 cost of kicking the ball to the opponent afterward). And field goals of this length (the article estimates 54 yards) succeed roughly 40% of the time. If the kicker misses, the opposing team would take over from the spot of the kick, which the example puts at the 45, producing an outcome of -1.8 expected points for the coach’s team. So taking into account the expected points from failure and success, and the likelihood of each, the expected points of a field-goal attempt is -0.02. A similar calculation for going for first down—expected points from success or failure, taking into account the likelihood of each) yields an expected point-value of +0.36. Numerically, going for it is by far the best outcome. But as you can see from those tri-coloured charts at the top of the page, coaches rarely go for it in that situation: they tend to punt. In fact, those charts show that coaches ought to try to convert far more often than they do: invariably in short-yardage situations and frequently for mid-yardage. Only when the yards to gain rise above 11 is it always a better decision to punt than try to convert.

The bot’s strategy assumes that coaches generally want to maximise the point differential between his team and the other, meaning he wants to score as many as possible while ensuring the other team scores as little as possible. In other words, he wants to win. I’m not sure this is correct. I think not losing—or more precisely, not making a decision that could be seen to directly result in a loss—is a far more powerful motivator for most coaches. That would explain their widespread, short-sighted conservatism on fourth downs. Punting is the “safe” choice: if you punt and your opponent scores a game-winning touchdown, your defence failed to stop them. If you go for it and your opponent does the same, then your offense failed to convert and then your defense failed to stop them. Double failure! Think of the Monday-morning, talk-show quarterbacking! It’s a coach’s nightmare. Coaching to not-lose rather than to win, coaching conservatively, exposes coaches to fewer embarrassing failures, and coaches (yes, I’m looking at you, Norv Turner) can fail consistently and unembarrassingly and still have long careers.

Readers' comments

There is a potential selection bias that I can't tell if 4th Down Bot has controlled for. If coaches are good at predicting when they'll pick up the first down (their team has momentum, makes plays when it counts, a fresh o-line, etc.), that would cause the measured success rate to be artificially high. A great way to improve the 4th Down Bot would be to look at field position and length of current drive, or previous success rate on 3rd and 4th down. Okay, improvement might be getting ahead of myself, but it'd be interesting to see. My instincts say a lot of coaches do play it conservative relative to what point maximisation would predict, but that 4th Down Bot overestimates the usefulness of going for it.

"As you can see from those tri-coloured charts at the top of the page, coaches rarely go for it in that situation: they tend to punt."

Maybe on 4th and 10, but not otherwise. Coaches often go for it in the range of yards where punting doesn't provide enough of a gain in field position, and field goals are more likely to miss, but only when fewer years are required.

Before 1974, coaches would always try the field goal, because the goalposts were at the front of the end zone, 10 years closer, and misses left the ball at the 20 yard line. The rules were changed in 1974, with the goalposts moved to the back of the endzone, making field goals from a given location 10 yards longer, and the ball returned to the line of scrimmage after a miss, in your example the 38.

It took a while for coaches to adjust. The first adjustment was to punt and try to have the ball downed or go out of bounds inside the 10 yard line, pinning the opponent back.

The first coach to realize what your article implies was Hall of Famer Bill Parcells of the New York Giants. Parcells was a conservative coach, who favored ball control and defense. But he figured out that going on fourth down, in certain situations, was a conservative defensive play, because you kept the other team from having the ball.

Other coaches copied his success. The "go for it" zone is approximately the 30 yard line to the 45, depending on the number of yards to go and how good your field goal kicker is.

What the 4th Down bot implies is that the number of yards to go at which going for it makes sense is longer than is generally believed. But that's only because the NFL has in effect become arena football.